1. Field of the Invention
The present invention relates to a mainframe storage controller and a mainframe volume virtualization method.
2. Description of the Related Art
For example, financial institutions and others use mainframes to make use of large amounts of data in their business operations. Storage controllers, which provide volumes for use by mainframes, are connected to the mainframes. The amount of data handled by mainframes is increasing every day. Accordingly, disk drives are being added to the storage controllers, and/or new storage controllers are being introduced into systems in response to the increasing data quantities.
However, there are limits as to how many disk drives can be added. When a plurality of storage controllers is introduced into a system, maintaining and managing this system is troublesome, and the storage areas of the respective storage controllers cannot be used effectively.
Now then, although not mainframe storage controller technology, technology for combining and virtualizing a plurality of volumes into one virtual volume is known in a so-called open storage controller (JP-A-2000-242434).
In the above-mentioned prior art, a plurality of real volumes of an old-fashioned storage controller can be combined into a single virtual volume and provided to a server. However, the above-mentioned prior art is for an open storage system, and cannot be used as-is in a system comprising a mainframe. This is because the method for handling data differs between a mainframe and an open system.
Furthermore, simply virtualizing a plurality of real volumes into a single virtual volume actually raises the risk of lower access performance. This is because, when old data is needed to process a write command, the old data must be read out from the respective real volumes for each write command issued by the mainframe.